Cholera. Lesson № 6

1. CHOLERA

Department of Microbiology,
Virology & Immunology
Ass. Prof. E. O. Kravtsova

2. Cholera dates back to the most ancient times. There were 7 pandemics

1. 1817-1823
2. 1826-1837
3. 1846-1862
4. 1864-1875
5. 1883-1896
6. 1900-1926 Caused by V.cholera
7. 1961-1963 Caused by V.cholera El Tor

3.

4.

• The bacterium had
been originally
isolated in 1854 by
Italian anatomist
Filippo Pacini, but
his results were
not widely known
around the world.
Filippo Pacini

5.

John Snow (1813-1858) found a link
between cholera and contaminated drinking
water in 1854.
He proposed a microbial origin for
epidemic cholera in 1849 and in his major
state of the art review of 1855 he
proposed a substantially complete and
correct model for the aetiology of the
disease.
In two pioneering epidemiological fieldstudies he was able to demonstrate that
human sewage contamination was the most
probable disease vector in two major
epidemics in London in 1854.
John Snow

6.

• Robert Koch
identified
• V. cholerae
in 1885.
Robert Koch

7.

Robert Koch
Isolator of V.cholera
Nobel of Medicine,1905

8.

9. Taxonomy

FAMILY VIBRIONACEAE
Genus: Vibrio
Species: V.cholerae
Biovars: Cholerae (1883) and El Tor (1906)

10.

Although there are more than 130 different
serogroups of V. cholerae, most epidemics are
associated with a single serotype, V. cholerae
O1.
In 1992 V.cholerae serogroup O139 (Bengal)
was registered as a new causative agent of
cholera.

11.

12.

13. FAMILY VIBRIONACEAE VIBRIO CHOLERAE

Gram «-» curved rods
Spores «-»
Capsula «-»
They are motile - monotrichous
V. cholerae has two circular chromosomes
Aerobes or facultative anaerobes
Growth best in alkaline nutrient agar, pH 8.2
at t= 37C
• Colonies are small, moist, translucent, round,
bluish.
• In 1% peptone water, growth occurs in about 6
hours as surface pellicle.

14. TSBC agar

15. Biochemical properties

• Ferment glucose, mannitol, maltose, mannose,
sucrose (acid), but not arabinose and lactose.
• Indole is formed H2S «-»
• Nitrates are reduced to nitrites
• Catalase and oxidase test are positive
• Methyl red and urease test are negative
• Gelatin is liquefied

16. Heiberg, group 1

• Mannose «+» acid
• Saccharose «+» acid
• Arabinose «-»

17. VIBRIO CHOLERAE

• Antigens: H - flagellar , is common for genus
Vibrio
O-somatic, is type specific
O1 and O139
O1 - A, B, C.
AB – Ogava, AC – Inaba,
ABC – Hikojima.

18. Resistance

• Susceptible to heat, drying, acid and common
disinfectants but resist alkaline medium.
• Destroyed at 55С in 15 minutes
• Killed in few minutes in gastric juice.
• Survive more 4 weeks in river water.
• On food stuff survive for 10 days.

19. Toxin Production

• V.cholera produced enterotoxin called
cholerogen which has a powerful toxic
effect and causes profuse, watery diarrhea.
• V.cholera produced collagenase,
decarboxylase, lipase, mucinase and
neuraminidase

20. Cholerogen

• Toxin binds to the plasma membrane of
intestinal epithelial cells and releases an
enzymatically active subunit that causes
a rise in cyclic adenosine
monophosphate (cAMP) production.
• The resulting high intracellular cAMP
level causes massive secretion of
electrolytes and water into the intestinal
lumen.

21.

Cholera enterotoxin (cholerogen-exotoxin) is produced by the
pathogen as it grows in the infected human gastrointestinal tract.
The enterotoxin, which consists of two molecular subunits, attaches
to the cell membranes of intestinal epithelial cells.
The B subunit binds to molecules on the cell surface and propels the
smaller A subunit into the cell, where it stimulates adenylate cyclase,
a membrane-associated enzyme that catalyzes the formation of cyclic
AMP (cAMP).
The accumulation of cAMP results in massive secretion of salts and
water from each affected cell.
The rapid loss of water produces a watery diarrhea that may cause a
cholera patient to lose 20 liters of fluid daily.
Such a dramatic loss of water leads to severe dehydration, thickening
of the blood, a decrease in blood volume, circulatory collapse
(shock), and death if not rapidly treated.

22. Disease in Men

Cholera is transmitted
by the fecal-oral route
Source of infection:
patients, carriers and
contaminated water
Symptom of diseases:
Weakness
Vomiting
Diarrhea

23.

Vibrio cholerae attachment and colonization in experimental rabbits. The events are assumed to be similar in human
Scanning electron microscopy
during early infection. Curved
vibrios adhering to epithelial
surface.

24. Development of diseases

Phases
Cholera Interitis
Characterize by
diarrhea for 1–2 days
In some cases,
infectious process
terminate and
patient recover
Cholera
Gastroenteritis
Characterize by profuse
diarrhea & continue
vomiting lead to
dehydration of body &
decrease body
temperature
Cholera Algid
Skin becomes pale due
to loss of water, cyanosis,
decrease body
temperature that leads to
dyspnoea, uremia,
coma & death
Cholera Sicca
Occur in no. of cases
Characterize by absent
of diarrhea & vomiting
Death occur due to
severe intoxication

25. Symptom of disease

rice water stool

26.

27. Rapid Diagnosis

Material: feces, vomit, drinking water
Inoculate into 3 test tubes
Put in thermostat (t=37C, 6 hours)
Results:
1% peptone water
•Prepare
micropreparation
•Gram’s method
•Motility exam
•Slide Agglutination
with antisera
1% peptone water
+ 01 antisera
If <+> & present cholera
clumps
1% peptone water
+ 0.5% starch
•Add Lugol iodine 2-3 drops
•Starch + Lugol => blue
•V.cholera ferment starch =>
color not change

28.

Bacteriological Examination
Day
1
Task
•Inoculation of investigated material on alkaline Agar & 1% peptone water (t=37c,
6-10 hour, 24h)
•Investigation of cultural properties
•Investigation of morphological & tinctorial properties by Gram method
Result
•In peptone 1% water there is delicate
pellicle on surface
-On alkaline agar colonies are
circular, smooth, moist, transparent,
colorless with bluish shinny
•Gram <-> comma shaped rod
•Motility exam
+
•Slide agglutination reaction with 01 cholera antiserum
+
•Isolation of pure culture on slant alkaline agar (t=37c,18-24h)
2-3
Identification of pure culture
•Morphological & tinctorial properties
•Investigation biochemical properties
•Study antigenic properties: Slide Agglutination Test
( with 01 antiserum & antiserum Inaba & Ogawa)
•Susceptibility to bacteriophages, polymyxin B , hemolytic activity ,
• Foges-Proskauer reaction
•Gram<-> comma shaped rod
Mannose <+> (a)
Sucrose <+> (a)
Arabinose<->
+
+

29.

DifferIdeIens of Biovars of
Cholera Vi
V.Cholerae
biovar
Cholerae
V.Cholerae
biovar
El Tor
Sheep erythrocytes hemolysis
-
+
Sensitivity to polymixin B
+
+
-
+
Hemagglutination with chicken
erythrocytes
-
+
Foges-Proskauer reaction
-
+
Differentiation properties
Lysis by bacteriophages
–«C» Phage IV
–Phage El-Tor

30. Treatment and Immunoprophylaxis

In treating cholera, antibiotics, and continual replacement of
fluids and electrolytes are recommended. The fluid and
electrolyte balance can be maintained by the oral or
intravenous administration of electrolytes in the presence of
glucose. The glucose is essential because it stimulates uptake
of sodium chloride and subsequent osmotic absorption of
water.
Two types of vaccines against cholera are available, but they
are only about 50 percent effective and confer immunity for
only 6 months. In its current state, the vaccine is useless for
preventing disease among residents of endemic areas.
Several newer vaccines, some composed of toxic fragments,
are being tested for use in endemic areas.

31. Treatment

Cholera bacteriophages
Antibiotic of Tetracycline group
Pathogenic therapy
Control of dehydration

32. Prophylaxis

Immunization with vaccine
Water supply disinfection
Hospitalization
Isolation